Evaluation of volatile organic compounds coupled to seasonality effects in indoor air from a commercial office in Madrid (Spain) applying chemometric techniques

Volatile organic compounds (VOCs) concentrations depend on several sources and factors, such as temperature, ventilation, and humidity. Sources can be external atmospheric pollution or indoor release from furniture, coatings or occupants. In this context, this study focused on quantification of VOCs present in a confined atmosphere in a commercial office in downtown Madrid, Spain. The influence of seasonal changes in VOCs concentrations was evaluated using chemometric approaches. Indoor air was systematically monitored for one year using stainless steel tubes filled with Tenax® TA. Sampling was conducted one week a month, for three days during that week (Monday, Wednesday and Friday) for 60 min, every 2 h, totaling 24 h, using an autosampler carousel. The analyses were performed using thermal desorption, and compounds were analyzed by a gas chromatograph coupled with a mass spectrometer. The correlation between these compounds and their concentrations, climatic variations, seasons, among others, were explained by multivariate statistics. Considering the current legislation in Spain, only benzene was present above the maximum permissible concentration (threshold value < 1 μg/m³) from all analyzed compounds. The results indicate that concentrations are related to significant environmental changes, such as ventilation, the number of occupants in the office and types of activity undertaken in the environment. The chemometric analyses allowed the identification of structure analyses correlations between multiple variables for the one-year study. These results underscore the importance of indoor atmosphere studies and chronic exposure to these contaminants.